"You can keep them on the show for six years and people will criticize you for not being realistic, or you can be really true to life and say when they started the show they were very clearly sophomores and they should graduate at the end of their senior year," he told the industry paper before adding, "more characters are leaving than are staying."

The show is set to return for its third season premiere on September 20. Murphy says he's already talked about his decision with two of the actors. "We made that decision and I involved Chris and Lea and they thought that was a good idea. They both trust the writing and trust me and felt that it would be great to have an open and closed experience for them to go out while they were on top," he said.

Murphy told the industry paper that he has not spoke with Monteith about his character's graduation but said, "He knows he was a sophomore when the show started."

"I'm much more interested in Lea's character," he said about the third season. "Not so much on her relationship with Finn, but more on what her dreams are beyond high school and how she plans on getting them."

Previously Murphy expressed that the show will be able to continue successfully without those characters because "We've got Matt Morrison and Jane Lynch who will stay and be the male and female lynchpins of the series."

He added, "But I think the fun thing about the show is it's a celebration of youth and talent and I think that just like with the original cast, I think finding those young unknown people and giving people an opportunity to break into the business and become stars is a really fun and exciting thing and is the spirit of the series."

"Glee" will also get new blood from whichever contestant wins the reality series "The Glee Project," which Murphy also appears in as a judge. The winner of the reality series nabs a seven-episode arc on "Glee," a recording contract and will get to go on the "Glee" tour next year with the cast.

"It's sort of a great, I think, opportunity for somebody to really sort of step into a spotlight and shine, which was the goal of the show all along anyway," Murphy said of the show, which airs on Sundays on Oxygen at 9 p.m.